Generator control system



March 20, 1951 R. M. CRITCHFIELD ET AL 2,545,633

GENERATOR CONTROL SYSTEM Original Filed Aug. 22, 1946 3/ WK f7 ff Z2 /M VE-A/TOE s 6055,67- M OB/Td/lF/E-LD ANQ A 04 A. Scum E1056 125: ,4?- TOE/VEYS Patented Mar. 20, 1951 UNITED PATENT .iOFF-ICE .GENERATQR CONTROL SYSTEM cRobert M. Critohfield and Paul L. Schneider, .Anderson, Ind., assignors. to General. Motors Corporation, Detroit, Mich., a corporationof Dflewa Original application August 22, 1946, Serial No. -692,352; no.w Patent N0.'2,498,793, dated-Febru- ..ary 18,1950. Divided and this application July 12 1194 t ifllN 103,563

Cl im .1 This invention. relates to control ineans for ,variable ratio drive to,be used with automotive generators.

-This application is a division. of original-application, Serial. No; 692,352,. filed August 22,; 19.45,

,tors, some means for contrplling -the slip of-the I coupli i nec a y- An object, of theinven on is terrovi tor-Vib control of theslip of an electrical couplinginsuch manner that the requ red.. e at u p t i be obtained at lowengine speeds while, in; the higher speed range of the engine, thegenerator speed, will not become excessive.

In the disclosedembodiment of the invention, the excitation of the energizingcoil of the coupling is controlled in .responseto, generator per- 1 formance.- Thegeneratorfield and the coupling coil are connected inseries and the currentwfiflwing thereinis controlled ,by current and voltage regulators.

Further objects and advantages of the present invention will'be apparent from the following .qdescription, re fere-nce being. had to the accompanying drawings, wherein a preferred embodiment of the present invention .is. clearly shown.

In the drawings:

Fig. 1 is a wirin diagram of one embodiment v of-the invention.

Fig- 2 isa longitudinal sectional view ofa typical electromagnetic coupling.

IIIFig. 1,;the line] designatesan engine driven shaft. The circleC- designates an electromagnetic coupling for connecting the shaft ID with shaft 1 I which drives generator G. The slip of coupling C isdependent upon the current flowing through the coupling coil 12. A form of..electromagnetic coupling is:v disclosed in Fig fihaft ,i IJ is journaled in bearings 13 supported by a bracket H. To shaft ID there is connected by a key I4 a plate IE to which screws I! attach a magnetizable shell or rotor l8, the interior surface of which is providedwith a pluralit of longitudinal extending grooves) equi-anguiarly spaced and each receiving a copper strap 20. The ends of all of the straps 2D are connected with rings 2l a nd- 22 thus providing a squirrel page rotor construction.

The shaft l0 supports apinbearing 24 and aball bearing 25 upon which is journaled armagnetizable shaft 26 to which screws Z'Iattach aplate 28 connected to or integral with generator shaft l I. A spacer 29 located within the shaft 26 andre- ,tained by the plate 28. holds the bearing 25 in position within the shaft 26. Shaft EB -provides ,pole pieces 30 which are diametrically opposite and which are located between diametrically opposite pole pieces 3|, extending from a plate-32 supported by the shaft-26, said shaft having a shoulder a against which theplate 32 is forced by the tightening of a nut 33 threadedly engaging the left end of the shaft 26 there being. awasher 34 between the nut. and the plate 32. The coupling field coil J2 of'r-ing formation is supported by the shaft26 and is embraced bythepole pieces and 3| each, of which has an angular span. of

slightly less than 90. The pole pieces Sil -will have polarity opposite tothe polarity of the pole -pieces 3l. The coil i2 isconnected by wires 35 I and ;36 with slip ring 31 and 58 insulatingly supported upon the shaft 36 by non-conducting sleeve'39, The rings 31, and 38 are engaged re-' spectively bybrushes M and 42. The coupling 0 ;(Fig. 2) therefore consists chiefiy of a rotor i8 and a rotatingfield; ill-and which includes the magnetizable shaft 26, the coupling field coil 12 and pole pieces 30 and; I alternatively of, opposite .polarity each pole piece spanning circumferentially somewhat lessthan v90". A coupling of this type is known as an electromagnetic coupling.

'In thesystem shown in Fig. 1, thef eld coil-F of the generatorand the field vcoil 12 of the coupling are connected in series. The current through,.both windings is controlled by current regulator 10 and a yoltage; regulator 80, the -operation, of which causes a; decrease in the current flowingthrough coils -;l2 and F as the speed of the generator increases and thereby reduces the speed range through which the generator must operate. .The closing of. switch-58 connectsthe battery charging line with wire 5,! leading to field coil F, coupling field coil 12 and resistance 82 To terminal. 12 there is cooperating with a core, not shown, which is surrounded by the coil H. Blade 13 carries a contact l5 normally engagin a contact 16 connected by wire 71 with voltage regulator coil 84 connected with wire 8 I. Wire 18 leads from terminal 12 to voltage regulator contact 85 normally engaged by a contact 86 carried by a leaf spring blade 81 attached to a terminal 88 which is grounded. Blade 81 carries an armature 89 cooperating with a core (not shown) surrounded by coil 84 and also by a coil 90 which is grounded at one end and is connected at the other end with the battery charging line and is therefore responsive to generator voltage. Coil 84 is responsive to the current flowing through the generator field. The regulators and 80 operate in the usual manner to control the current flowin through generator field coil F and coupling field coil [2. So long as the contacts of the regulators remain closed, the resistances 82 and 83 are by-passed to ground. When the current in coil H exceeds a certain value, the contacts of regulator II are separated so that the current flowing through the coils F and I2 is reduced b the resistances 82 and 83 in parallel. When the voltage in coil 9! exceeds a certain value, the contacts of voltage regulator 80 are separated and the resistance 83 is open circuited to reduce the current flow in these coils F and I2. The current and voltage regulators operate to reduce the field current as the speed of the generator increases, and also to reduce the current in coupling coil l2 which reduces the speed range through which the generator must operate.

From the foregoing description of one embodiment thereof, it is apparent that the present invention provides means responsive to generator performance for controlling the excitation of the coupling coil. More specifically, the excitation of the coupling coil is controlled by current and voltage regulators.

In the present invention, the closing of the ignition control switch 58 prior to starting the engine connects the coupling coil with the battery so that even prior to closing of the cut-out relay contacts 61, 68 the coupling is ready to effect ,maximum coupling ratio between the engine and the generator whereby the generator voltage attained at low engine speed is sufficient for battery charging.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A generator speed-limiting control system for use on automotive vehicles and comprising a generator which is driven at varying speeds by the vehicle propelling engine, said generator having a shunt field winding, a storage battery charged by the generator, a generator-battery circuit including a relay for connecting the gen erator and battery when the generator is driven at a speed such that its voltage exceeds the counter-voltage of the battery and for disconnecting the battery from the generator when the genera tor speed is at such relative low value that the battery can discharge through the generator, an electromagnetic coupling normally connecting the engine with the generator at a drive ratio required for the closing of the relay and the charging of the battery at relatively low engine speeds, said coupling havin an exciting coil and providing for coupling slip which is least when the ener- 4 gization of the coil is greatest and vice-versa, a circuit for connecting the coupling coil with the generator-battery circuit between the relay and the battery and including a manually operated switch and two normally by-passed current controlling resistances, each of the by-passes including a pair of normally closed contacts, an electromagnet responsive to generator current output for opening one of the pairs of contacts when output current exceeds a predetermined value and an electromagnet responsive to generator voltage for opening the other pair of contacts when generator voltage exceeds a predetermined value.

2. A generator speed-limiting control system for use on automotive vehicles and comprising a generator which is driven at varying speeds by the vehicle propelling engine, said generator having a shunt field winding, 9, storage battery charged by the generator, a generator-battery circuit including a relay for connecting the generator and battery when the generator is driven at a speed such that its voltage exceeds the countervoltage of the battery and for disconnecting the battery from the generator when the generator speed is at such relative low value that the battery can discharge through the generator, an electromagnetic coupling normally connecting the engine with the generator at a drive ratio required for the closing of the relay and the charging of the battery at relatively low engine speeds, said coupling having an exciting coil and providing for coupling slip which is least when the energization of the coil is greatest and vice-versa, a circuit for connecting the coupling coil with the generator-battery circuit between the relay and the battery and including a manually operated switch in series with the shunt field winding of the generator and with circuits in parallel comprising a first branch comprising, in series, two pairs of resistance by-passing contacts, and a second branch comprising a first resistance in parallel with one pair only of said pairs of contacts and a third branch comprising a second resistance in parallel with the other branches, an electromagnet responsive to generator current output for opening one of the pairs of contacts when output current exceeds a predetermined value and an electromagnet responsive to generator voltage and having a coil in the first branch for opening the other pair of contacts when generator voltage exceeds a predetermined value.

ROBERT M. CRITCI-IFIELD. PAUL L. SCHNEIDER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

